DE2203830A1 - Steel with great magnetic permeability - Google Patents

Description

DR. BERG DIPL.-ING. STAPF

PATENTANWÄLTE 8 MUNICH 8O. MAUERKIRCHERSTR.

Dr. Berg Dipl.-Ing. Stapf, 8 Manchen 80, MauerkircherstroB »45 · Your sign Your writing Our sign

22 o69

date

Lawyer file 22 069

Acieries de Paris & d'Outreau Paris / France

Steel with great magnetic permeability

The invention relates to cast steel with high magnetic permeability and a high elastic limit, which keeps its mechanical and magnetic properties even after a Heating, for example as a result of brazing, maintains.

VII / bo

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The development and manufacture of large electrical, rotating machines has led the designers to to look for cast steel with improved elastic limits for the execution of massive poles, which by their mass and the speed of rotation are exposed to considerable mechanical stresses.

There are several types of cast steel that have the mechanical properties required by designers for heavy-duty applications electrical material correspond; however, a decrease in the magnetic properties, so they could not be used.

Investigations of the magnetic permeability of different types of cast steel show for one and the same magnetic field that the magnetic induction decreases as the mechanical properties increase.

In the following table, which is an excerpt from "Stahlguß, Edition 1966, page 142", the magnetic induction is in Tesla depending on field strengths of 25 A / cm, 50 A / cm, 100 A / cm for non-alloy steels with better ones mechanical properties shown.

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Steel grade N ° DIN Magnetic
strength of: induction for a field description 1 25 A / cm 5o A / cm loo A / cm GS 38 1 .o443 1.45 l, 6o 1.75 GS 45 1 .0551 l, 4o 1.55 1.7 · ο GS 52 1 .0553 1.35 1.55 l, 7o GS 60 l, 3o l, 5o 1.65

(1 Tesla = lo ^H Gauss)

DIN: German industrial standard

It is even possible to establish a relationship between magnetic induction and Brinell hardness. For example, at a field strength of 25 A / cm, the magnetic induction ranges from slightly more than 1.5 T for 13o Brinell to slightly less than 1.3 T for 21o Brinell for non-alloyed and simply standardized steel samples.

The study of the influence of elements normally found in ordinary non-alloy steel shows that the best magnetic properties are obtained for the lowest levels of carbon and manganese that can still get flawless steel castings.

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For example, the applicant has been making items such as AC machine casings on a regular basis for several years Made of cast steel with high magnetic permeability with a tensile strength of the order of 4o to 45

2 ρ

DaN / mm (kg / mm). In the table below is the magnetic Permeability in Gauss for a steel with C, Mn and Si in the given ratios (in percent by weight) shown.

Magnetic field in A / cm 15 29 6o 12o

Specification of the construction 13 5oo 15 5oo 17 ooo I8300 2o teurs

Steel C Mn Si 14 2oo 15 800 17 2oo 18 600 2o 4oo 0.113 ö75f 075Ϊ

When examining cast steel with a higher elastic

• 2 2
When the strength limit is greater than 45 DaN / mm (kg / mm), those skilled in the art have found a decrease in the magnetic properties (the magnetic induction is expressed in Gauss).

C Mn Si R E A 25 A / cm 5o A / cm 10o A / cm

0.332 l.5o 0.38 73.3 45.3 15 12,4oo 15.I00 17,150

o, 357 1, ^ 9 o, Ho 73.3 46, ο 14 12,600 l4,8oo 17.loo

o.4o8 1.12 o.91 81.5 47.1 13 II.900 I4.35o 16,600

o.4o2 0.83 o.4l 76.9 48.8 17 13,700 15,500 17,000

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· - C ■ _

2 2 R: tensile strength in DaN / mm (kg / mm)

2 2 E: elastic limit in DaN / mm (kg / mm) A: elongation in %

The investigation of steel with 2.5o weight percent Ni has shown very satisfactory magnetic properties, but it does not have the same elastic limit, all the more so since the steel also retains its mechanical properties must, if it is briefly heated to a temperature of the order of 7oo ° C, which corresponds to a temperature which is achieved during brazing.

Steel C Mn Si Ni (in percent by weight)

o72T 075H 0T3S 2.51

machined for R = 63.7 DaN / mm ² (kg / mm ² ) E = 37.2o DaN / mm ² (kg / mm ² ) A = 26.3 %

The thrill in Tesla is with a permeability knife Illiovici - model C measured.

Field strength 5j5o 7> 5o Io 15 25 5o loo 15o 2oo 300 ^f ioo in A / cm

Excitation 0.56 o, 84 I, o8 1.36 1.55 1.69 1.82 1.93 1.98 2, o4 2, 08 in T

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The object of the invention is therefore to create a series of steels that, despite the heating during brazing a solid piece has a high elastic limit in every respect and at the same time a high magnetic permeability guarantee.

These steels are characterized by:

a carbon content that is limited to 0.3o percent by weight,

a silicon content between 0.2 and 1.o percent by weight, a manganese content of 0.3 to 1.2 percent by weight, a nickel content of 2 to 3 percent by weight, a chromium content of 0.3 to 1 percent by weight and a molybdenum content of 0.2 to 1 percent by weight.

The steels according to the invention preferably have a silicon content of 0.25 to 0.45 percent by weight, a manganese content of 0.5 to 0.9 percent by weight, a nickel content of 2 to 2.5 percent by weight, a chromium content of 0.3 to 0.15 percent by weight and a molybdenum content of 0.4 to 0.6 percent by weight.

Such steels ensure the following mechanical properties:

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Tensile strength ^ 65 DaN / mm (kg / mm)

Elastic limit at 2% ^ 45 DaN / mm ² {kg / mm ² )

Elongation in # ^> 16

Impact strength KCU> 7 DaJ / cm ² (mkg / cm ² )

The steels have the following magnetic properties:

For a magnetic field of: 5o A / cm I50 A / cm 3oo A / cm An excitation of: 1.6 T 1.85 T 1.92 T

These steels are at a temperature of 1 6oo ° C by conventional steel production processes, for example in a Electric arc furnace.

The present invention includes the use of these steels in all fields of application where high magnetic properties are required at the same time with a high elastic limit; at the same time it creates possible applications for solid pieces, where the mechanical and considerable stretching or tensile properties are retained in a casting should stay. A particularly advantageous application is the production of pole masses in electrical machines, especially in generators; for this application are

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in the case of the steel according to the invention, the mechanical and magnetic properties of the pole masses are noticeable at the same time improved.

- patent claims -

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Claims (2)

Claims 1. Steel with a large magnetic permeability and a high elastic limit, characterized by a carbon content that is limited to 0.3o percent by weight is, due to a silicon content of 0.2 to 1.2 percent by weight, a manganese content of 0.3 to 1.2 percent by weight, a nickel content of 2 to 3 percent by weight, a chromium content of 0.3 to 1.0 percent by weight and a molybdenum content of 0.2 to 1.0 percent by weight. 2. Steel according to claim 1, characterized by a silicon content between 0.25 and 0.45 percent by weight, a manganese content between 0.5 and 0.9 percent by weight, a Nickel content between 2 and 2.5 percent by weight, a chromium content between 0.3 and 0.15 percent by weight and a molybdenum content between 0.4 and 0.6 percent by weight. 209845/0616 ORIGINAL INSPECTED